Conventional Data Augmentation Methods Research Articles

Feature decoupling and regeneration towards wifi-based human activity recognition

Gesture recognition using WiFi is vital for human–computer interaction, smart homes, smart spaces, and elderly care. WiFi signals are non-stationary, sensitive to the environment, and traditional pattern recognition-based HAR methods incur exorbitant training and deployment costs due to their reliance on the quality and quantity of training data. While there has been extensive research on enhancing HAR techniques, the efficiency of the system is still limited by the scarcity of training data and identity-action feature coupling. This research focuses on attaining gesture recognition across multiple users with a limited number of samples. Our findings show that the conventional data augmentation methods are incapable of facilitating the system in attaining sample diversity. As a result, we propose a training-free augmentation strategy as a means to provide adequate training data. Unlike the conventional data enhancement approach, this scheme aims to develop data processing methods that differentiate between various samples in practical applications. Consequently, it enhances data pertinent to specific HAR assignments effectively. To effectively extract action features in WiFi samples, an unsupervised cross-user domain sample generation (CUDSG) model is proposed. This model generates virtual gesture samples for new user domains by decoupling and recombining gesture and identity features. This extends the sensing boundary of the system to new user domains without requiring a significant number of users to participate. Model performance was evaluated using various classifiers, such as SVM, KNN and CNN. The results demonstrate a significant improvement in average classification accuracy from 57.3% to 98.4%. This indicates that CUDSG is a highly effective tool for enhancing the performance of existing gesture recognition techniques.

Artificial intelligence-based speckle featurization and localization for ultrasound speckle tracking velocimetry

Deep learning-based super-resolution ultrasound (DL-SRU) framework has been successful in improving spatial resolution and measuring the velocity field information of a blood flows by localizing and tracking speckle signals of red blood cells (RBCs) without using any contrast agents. However, DL-SRU can localize only a small part of the speckle signals of blood flow owing to ambiguity problems encountered in the classification of blood flow signals from ultrasound B-mode images and the building up of suitable datasets required for training artificial neural networks, as well as the structural limitations of the neural network itself. An artificial intelligence-based speckle featurization and localization (AI-SFL) framework is proposed in this study. It includes a machine learning-based algorithm for classifying blood flow signals from ultrasound B-mode images, dimensionality reduction for featurizing speckle patterns of the classified blood flow signals by approximating them with quantitative values. A novel and robust neural network (ResSU-net) is trained using the online data generation (ODG) method and the extracted speckle features. The super-resolution performance of the proposed AI-SFL and ODG method is evaluated and compared with the results of previous U-net and conventional data augmentation methods under in silico conditions. The predicted locations of RBCs by the AI-SFL and DL-SRU for speckle patterns of blood flow are applied to a PTV algorithm to measure quantitative velocity fields of the flow. Finally, the feasibility of the proposed AI-SFL framework for measuring real blood flows is verified under in vivo conditions.

A deep learning self-attention cross residual network with Info-WGANGP for mitotic cell identification in HEp-2 medical microscopic images

BackgroundThe identification of human epithelial type-2 mitotic cell patterns in the indirect immunofluorescence images (IIF HEp-2) is a critical step for autoimmune diseases computer-aided diagnosis (CAD) systems. Recognition of HEp-2 cells in the mitotic phase is clinically vital for validating the HEp-2 samples and assisting in diagnosing specimens with mixed patterns. Typically, mitotic cells are rarely observed in the HEp-2 specimen images, resulting in a significant skewness of the available medical datasets towards the majority of interphase (non-mitotic) patterns. MethodsIn this paper, a deep learning framework is proposed based on a self-attention deep cross-residual network with an efficient generative adversarial network (GAN). The proposed framework consists of two consecutive steps. First, the problem of imbalanced data of minority mitotic against the majority interphase cells is remedied using Info-WGANGP approach in combination with the conventional data augmentation methods. Second, a downstream end-to-end deep learning Att-DCRNet is developed to classify the mitotic and interphase cell patterns of the IIF HEp-2 medical images. A comprehensive experimental study is performed to validate the effectiveness of the proposed framework against other state-of-the-art methods over the public medical dataset of UQ-SNP_HEp-2 Task-3. ResultsThe proposed framework demonstrates competitive classification results attaining a maximum performance of 84.10% F1-score, 84.70% Matthew's correlation coefficient (MCC), and 99.0% balanced class accuracy (BcA), which proves its applicability for automatically supporting an accurate diagnosis decision regarding the HEp-2 mitotic and interphase cell patterns. The source code is available at this link: https://github.com/Anaam-dl/AttDCRNet_with_InfoWGANGP.

Deep Transfer Learning Networks for Brain Tumor Detection: The Effect of MRI Patient Image Augmentation Methods

The exponential growth of deep learning networks has enabled us to handle difficult tasks, even in the complex field of medicine with small datasets. In the sphere of treatment, they are particularly significant. To identify brain tumors, this research examines how three deep learning networks are affected by conventional data augmentation methods, including MobileNetV2, VGG19, and DenseNet201. The findings showed that before and after utilizing approaches, picture augmentation schemes significantly affected the networks. The accuracy of MobileNetV2, which was originally 85.33%, was then enhanced to 96.88%. The accuracy of VGG19, which was 77.33%, was then enhanced to 95.31%, and DenseNet201, which was originally 82.66%, was then enhanced to 93.75%. The models' accuracy percentage engagement change is 13.53%, 23.25%, and 23.25%, respectively. Finally, the conclusion showed that applying data augmentation approaches improves performance, producing models far better than those trained from scratch.

Data Augmentation for Deep Graph Learning

Graph neural networks, a powerful deep learning tool to model graph-structured data, have demonstrated remarkable performance on numerous graph learning tasks. To address the data noise and data scarcity issues in deep graph learning, the research on graph data augmentation has intensified lately. However, conventional data augmentation methods can hardly handle graph-structured data which is defined in non-Euclidean space with multi-modality. In this survey, we formally formulate the problem of graph data augmentation and further review the representative techniques and their applications in different deep graph learning problems. Specifically, we first propose a taxonomy for graph data augmentation techniques and then provide a structured review by categorizing the related work based on the augmented information modalities. Moreover, we summarize the applications of graph data augmentation in two representative problems in data-centric deep graph learning: (1) reliable graph learning which focuses on enhancing the utility of input graph as well as the model capacity via graph data augmentation; and (2) low-resource graph learning which targets on enlarging the labeled training data scale through graph data augmentation. For each problem, we also provide a hierarchical problem taxonomy and review the existing literature related to graph data augmentation. Finally, we point out promising research directions and the challenges in future research.

Guided Random Mask: Adaptively Regularizing Deep Neural Networks for Medical Image Analysis by Potential Lesions

Data augmentation is a critical regularization method that contributes to numerous state-of-the-art results achieved by deep neural networks (DNNs). The visual interpretation method demonstrates that the DNNs behave like object detectors, focusing on the discriminative regions in the input image. Many studies have also discovered that the DNNs correctly identify the lesions in the input, which has been confirmed in the current work. However, for medical images containing complicated lesions, we observe the DNNs focus on the most prominent abnormalities, neglecting sub-clinical characteristics that may also help diagnosis. We speculate this bias may hamper the generalization ability of DNNs, potentially causing false predicted results. Based on this consideration, a simple yet effective data augmentation method called guided random mask (GRM) is proposed to discover the lesions with different characteristics. Visual interpretation of the inference result is used as guidance to generate random-sized masks, forcing the DNNs to learn both the prominent and subtle lesions. One notable difference between GRM and conventional data augmentation methods is the association with the training phase of DNNs. The parameters in vanilla augmentation methods are independent of the training phase, which may limit their effectiveness when the scale and appearance of region-of-interests vary. Nevertheless, the effectiveness of the proposed GRM method evolves with the training of DNNs, adaptively regularizing the DNNs to alleviate the over-fitting problem. Moreover, the GRM is a parameter-free augmentation method that can be incorporated into DNNs without modifying the architecture. The GRM is empirically verified on multiple datasets with different modalities, including optical coherence tomography, x-ray, and color fundus images. Quantitative experimental results show that the proposed GRM method achieves higher classification accuracy than the commonly used augmentation methods in multiple networks. Visualization analysis also demonstrates that the GRM can better localize lesions than the vanilla network.

Decoupled self-supervised label augmentation for fully-supervised image classification

Self-supervised label augmentation has emerged as an effective means to overcome the data scarcity problem for supervised vision tasks. Existing rotation-based self-supervised label augmentation methods either impose or relax the rotation invariance constraint on the primary classifier, which omit necessary supervisory information and may degrade the classification performance depending on the given working data. To overcome this problem, we propose a decoupled self-supervised label augmentation method to enhance the feature representation for fully-supervised image classification. Experimental results on diverse datasets demonstrate that the proposed method consistently outperforms state-of-the-art data augmentation methods. The proposed method is also complementary to conventional data augmentation methods, such as AutoAugment and Fast AutoAugment.

BiFA-YOLO: A Novel YOLO-Based Method for Arbitrary-Oriented Ship Detection in High-Resolution SAR Images

Due to its great application value in the military and civilian fields, ship detection in synthetic aperture radar (SAR) images has always attracted much attention. However, ship targets in High-Resolution (HR) SAR images show the significant characteristics of multi-scale, arbitrary directions and dense arrangement, posing enormous challenges to detect ships quickly and accurately. To address these issues above, a novel YOLO-based arbitrary-oriented SAR ship detector using bi-directional feature fusion and angular classification (BiFA-YOLO) is proposed in this article. First of all, a novel bi-directional feature fusion module (Bi-DFFM) tailored to SAR ship detection is applied to the YOLO framework. This module can efficiently aggregate multi-scale features through bi-directional (top-down and bottom-up) information interaction, which is helpful for detecting multi-scale ships. Secondly, to effectively detect arbitrary-oriented and densely arranged ships in HR SAR images, we add an angular classification structure to the head network. This structure is conducive to accurately obtaining ships’ angle information without the problem of boundary discontinuity and complicated parameter regression. Meanwhile, in BiFA-YOLO, a random rotation mosaic data augmentation method is employed to suppress the impact of angle imbalance. Compared with other conventional data augmentation methods, the proposed method can better improve detection performance of arbitrary-oriented ships. Finally, we conduct extensive experiments on the SAR ship detection dataset (SSDD) and large-scene HR SAR images from GF-3 satellite to verify our method. The proposed method can reach the detection performance with precision = 94.85%, recall = 93.97%, average precision = 93.90%, and F1-score = 0.9441 on SSDD. The detection speed of our method is approximately 13.3 ms per 512 × 512 image. In addition, comparison experiments with other deep learning-based methods and verification experiments on large-scene HR SAR images demonstrate that our method shows strong robustness and adaptability.

ProEGAN-MS: A Progressive Growing Generative Adversarial Networks for Electrocardiogram Generation

Electrocardiogram (ECG) is a physiological signal widely used in monitoring heart health, which is of great significance to the detection and diagnosis of heart diseases. Because abnormal heart rhythms are very rare, most ECG datasets have data imbalance problems. At present, many algorithms for ECG anomaly automatic recognition are affected by data imbalance. Conventional data augmentation methods are not suitable for the augmentation of the ECG signal, because the ECG signal is one-dimensional and their morphology has physiological significances. In this paper, we propose a ProGAN based ECG sample generation model, called ProEGAN-MS, to solve the problem of data imbalance. The model can stably generate realistic ECG samples. We evaluate the fidelity and diversity of the data generated by the model and compare the data distribution of the original and generated data. In addition, in order to show the diversity of the generated ECG data more intuitively, we manually checked the diversity and calculate the statistics of the data. The results show that compared with other ECG augmentation methods based on GANs, the ECG data generated by our model has higher fidelity and diversity, and the distribution of generated samples is closer to the distribution of original data. Finally, we established neural network models for arrhythmia classification, and used them to evaluate the improvement of the classification model performance by ProEGAN-MS. The results show that augmented data by ProEGAN-MS can effectively improve the insufficient sensitivity and precision of the classification model.

Label-preserving data augmentation for mobile sensor data

Data augmentation is important for training neural networks, especially when there is not enough data to train a network well. However, data augmentation that results in the loss of label information may reduce the performance of the model. Most conventional data augmentation methods have been developed for image- or sound-related tasks, in which case the label information of the augmented data is easily and intuitively verified by human observation. However, in the case of sensor signals, it is difficult to recognize whether there is a change in the label information of the augmented data. We propose a systematic data augmentation method to maximize the performance by automatically finding the range of augmentation that preserves the labels of the augmented data. The experimental results show that the proposed method to extract the label-preserving range is practical and that the retrained model using data augmented within this range improves the performance by at least 5% without the need to further optimize the model architecture.

Learning Convolution Neural Network with Shift Pitching based Data Augmentation for Vibration Analysis

Data augmentation is a common approach that been implemented in order to increase the training data quantity for Convolutional Neural Networks in signal processing, image recognition and speech recognition. However, the conventional data augmentation methods usually implement the window slicing and overlap window slicing methods in the bearing fault analysis. Meanwhile, the audio deformation approach such as time stretching and pitch shifting methods have been commonly used as data augmentation approach in speech recognition. Thus, this paper proposed a data augmentation based on shift pitching technique for the vibration signal. The relationship between the audio and the vibration signal is evaluated for a bearing fault analysis using Convolution Neural Networks. The new dataset produce by the data augmentation is used to increase the number of training dataset and to improve the Convolutional Neural Networks training performance. The result shows that the shift pitching based data augmentation method able to achieve higher training accuracy compared to the window sliding data augmentation. The combinations of all ratio pitch obtain 93% accuracy whilst the accuracy for a single rate pitch are between 81% to 91%.Thus, the proposed method is competent and able to improve the performance of bearing fault classification

Data-level information enhancement: Motion-patch-based Siamese Convolutional Neural Networks for human activity recognition in videos

Data augmentation is critical for deep learning-based human activity recognition (HAR) systems. However, conventional data augmentation methods, such as random-cropping, may generate bad samples that are unrelated to a particular activity (e.g. the background patches without saliency motion information). As a result, the random-cropping based data augmentation may affect negatively the overall performance of HAR systems. Humans, in turn, tend to pay more attention to motion information when recognizing activities. In this work, we attempt to enhance the motion information in HAR systems and mitigate the influence of bad samples through a Siamese architecture, termed as Motion-patch-based Siamese Convolutional Neural Network (MSCNN). The term motion patch is defined as a specific square region that includes critical motion information in the video. We propose a simple yet effective method for selecting those regions. To evaluate the proposed MSCNN, we conduct a number of experiments on the popular datasets UCF-101 and HMDB-51. The mathematical model and experimental results show that the proposed architecture is capable of enhancing the motion information and achieves comparable performance.

A novel data augmentation method to enhance deep neural networks for detection of atrial fibrillation

Automated detection of atrial fibrillation (AF) from electrocardiogram (ECG) recordings remains challenging in real clinical settings. Deep neural networks (DNN) emerge as a promising tool for the task of AF detection. However, the success of DNN for AF detection is hampered by limited size and imbalanced number of samples in datasets. We propose a novel data augmentation strategy based on duplication, concatenation and resampling of ECG episodes to balance the number of samples among different categories as well as to increase the diversity of samples. The performance of the data augmentation method was examined on an AF database from Computing in Cardiology (CinC) challenge 2017. A 2-layer long short-term memory (LSTM) network was trained with the augmented dataset. Its ability of AF detection was evaluated using a 10-fold cross validation approach. And F1 score was adopted as the metrics. The AF detection results show that the proposed method was superior to two conventional data augmentation methods: window slicing and permutation. The network was also submitted to the evaluation system of the CinC challenge 2017. The F1 score obtained by the network using the proposed data augmentation method was close to the winner (0.82 vs. 0.83). In summary, the proposed data augmentation method provides an effective solution to enhance the dataset for improving the performance of DNN in ECG analysis. Such a method promotes the application of deep learning in the analysis of ECG, particularly when the dataset is small and imbalanced.

Learning Data Manifolds with a Cutting Plane Method.

We consider the problem of classifying data manifolds where each manifold represents invariances that are parameterized by continuous degrees of freedom. Conventional data augmentation methods rely on sampling large numbers of training examples from these manifolds. Instead, we propose an iterative algorithm, [Formula: see text], based on a cutting plane approach that efficiently solves a quadratic semi-infinite programming problem to find the maximum margin solution. We provide a proof of convergence as well as a polynomial bound on the number of iterations required for a desired tolerance in the objective function. The efficiency and performance of [Formula: see text] are demonstrated in high-dimensional simulations and on image manifolds generated from the ImageNet data set. Our results indicate that [Formula: see text] is able to rapidly learn good classifiers and shows superior generalization performance compared with conventional maximum margin methods using data augmentation methods.

Improving Classifier Performance Using Data with Different Taxonomies

We propose a framework for improving classifier performance by effectively using auxiliary samples. The auxiliary samples are labeled not in terms of the target taxonomy according to which we wish to classify samples, but according to classification schemes or taxonomies that are different from the target taxonomy. Our method finds a classifier by minimizing a weighted error over the target and auxiliary samples. The weights are defined so that the weighted error approximates the expected error when samples are classified into the target taxonomy. Experiments using synthetic and text data show that our method significantly improves the classifier performance in most cases compared to conventional data augmentation methods.